Calibrating means for pitot venturi tubes



1948- H. w. STOLL 2,441,042

cumwrma MEANS FOR PI'I'OT vEu'run; mans Filed Apri1 25, 1946 IN VEN TOR.

Henry w 15' fol Z passesthrough the wall memo mans roa ri'ro'r VENTURE TUBES Henry W. Stoll, Rochester, N. Y., assignor, by

mcsne assi 1 ents, to the United States of erica as represented by the United States Atomic Energy Cossion Application April 25, 1946, Serial No. 664,815

2 Claims.

This inevntion relates in a velocity head meter.

Prior to the use of the present invention each Pitot-Venturi flow element was accompanied by a chart of calibrating values since it was found in practice that, regardless of the accuracy observed in constructing the parts, iiow elements having identical constants could not be produced. Consequently, when these Pitot-Venturi flow elements were used to perform identical functions it became necessary to supply a correction factor to each device used therewith, such as a diiierential pressure transmitter to compensate for the variable calibration constants of the individual Pitot-Venturi flow element in order to obtain equal results.

In accordance with the present invention a simple means is provided so that each Pitot- Venturi flow element will have the same calibration constant when compared with a given standard.

In accordance with a more specific aspect of the invention, there is provided a compensating ring which engages and is slidably mounted on theperiphery oi the Pitot-Venturi tube body so that it can be positioned and locked at a point on the tube body where the device has constants equal to that of a standard device.

The single drawing shows a sectional view of the Pitot-Venturi flow element I3 mounted within a chamber, such as a pipe or blower, wherein a gas'is caused to flow. The wall section It represents a section of the pipe or blower wall, and the'support l'l containing two channels I8 and 19, section l6, thus providing a means for communicating difierent pressures produced between a constricted throat it, of the element It, and an opening H to the channel I 8, to an outside instrument, such as a differen- "tial pressure transmitter. The support I! also provides support for the element l3. The diflerential pressure mentioned above is the pressure difierence between the direct impact pressure, as detected at opening H to the channel It, and the reduced pressure as detected at the constricted to means for calibrating Pitot-Venturi tubes of the type suitable for use 2, thePitot-Venturi tube body it and adapted to be secured at any desired position on the tube body by means of set screws it. The calibrating ring in causes an outward swirl of the gas passing at the outside of body ll, which swirl tends to carry along with it, gas molecules in the vicinity thereof. As the ring is brought nearer the region of the downstream end of the Venturi tube body, a greater amount of gas is "swept from this region, hence decreasing the pressure at the downstream end or exit which encourges more gas to flow through the throat l5 of the body II. The adjustable calibrating ring makes it possible to complete the necessary calibration adjustments on each Pitot-Venturi flow element at the laboratory bycomparison with a. desired standard. Therefore the adjustable calibrating ring I!) results in each Pitot-Venturi meter hav: ing the same calibration constants and precludes the necessity for individual treatment in the field.

What I claim is:

1. In a Pitot-Venturi flow element, a Venturi tube body adapted to be mounted in a stream of gas or the like, means communicating with the gas at two diflerent points adjacent the body,

and a barrier mounted externally of said tube,

said barrier extending across said stream and adjustable along said body to modify the flow of said stream around the same whereby the flow characteristics of said element can be changed to correspond with a given standard element.

2. In a Pitot-Venturi flow element, a Venturi tube body adapted to be mounted in a stream of gas or the like, means communicating with the gas at two diiierentpoints adjacent the body, and a ring encircling said body in engagement with the periphery thereof and adjustable along said body to modify. the flow of said stream throat l5 which communicates with the channel l9. As herein illustrated, the support I1 is provided with a threaded cap 0 which is used only until the element is ready for installation.

In accordance with the present invention there is provided an adjustable calibrating ring 10 which is slidably mounted on the periphery of around the same whereby'the flow characteristics 01' said element can be changed to correspond with a given standard element.

' HENRY W. STOLL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

